


Monster Mash

by DoctorV, GrayceAdamsArchive



Series: The World Does (not) Revolve Around Perrin Fletcher [4]
Category: Phineas and Ferb
Genre: Body Horror, Gen, Ghosts, Halloween, Halloween Special, M/M, Monsters, Skeletons, cartoon violence, decapitation (but not really), experiments gone wrong, heinz's inators fucking shit up again, its mostly silly, monster au, theres no actual gore
Language: English
Status: Completed
Published: 2015-10-08
Updated: 2016-03-02
Packaged: 2018-04-25 09:29:34
Rating: Teen And Up Audiences
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 2
Words: 5,998
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/4955143
Author URL: https://archiveofourown.org/users/DoctorV/pseuds/DoctorV, https://archiveofourown.org/users/GrayceAdamsArchive/pseuds/GrayceAdamsArchive
Summary: <blockquote class="userstuff">
              <p>
  <i>The dark shape under Perry’s hand twitched and then suddenly shot up in a flurry of movement. Eerie purple light spilled from what looked like a giant wing, and Perry yelped, falling back away from whatever Heinz had accidentally created. <i></i></i>
</p><p> </p><p> </p><p> </p><p> </p><p>  <i>An accident at Danville High causes a peculiar change in what seems like half the city, and as usual, Perry's caught right in the middle of the whole mess.</i></p>
            </blockquote>





	1. Chapter 1

**Author's Note:**

> This is mostly a just for funsies ficlet collection of some Monster AU written for the Halloween Special on APF. It's not really plot heavy, and doesn't affect the rest of TWDNR series, but does take place in that universe. There will (probably) be more chapters, but at this point in time it's just a one shot to explain what's happened. :) 
> 
> I'm also posting it like 3 days early because I am impatient.
> 
> Edit: Not complete, but I'm unlikely to add another chapter anytime soon, so I'm marking it as complete for now. If you'd like to know how it ends, check out the APF blog, there's a comic about it under the hspesh tag.

The explosion that rocked Danville High on Oct. 10th was smaller than most that had happened before, causing very little damage to the building itself. Nevertheless, it created a lot of smoke, so when Perry skidded to a stop in front of the open door to Heinz’s classroom, he quickly pulled the sleeve of his shirt down over his hand to cup it over his mouth and nose so he could breathe without hacking up a lung.

Walking into the dark classroom, Perry looked around with watering eyes, trying to spot where any of the students or Heinz might be. The strange ripple of energy that had followed the explosion had Perry tingling and feeling like his skin was trying to crawl off his body, but he ignored it best he could, searching for any sign of Heinz and his class.

Stumbling over a student’s backpack, Perry threw out an arm and caught himself on the edge of Heinz’s desk, which was lying on its side. Perry rapped his knuckles against it in his trademark knock, hoping to hear a response, but instead was only answered by silence and the quiet buzzing of the latest failed experiment.

“Heinz?” Perry croaked, squinting through the smoke as his throat ached. “Answer mae!”

There was a quiet shuffling noise from by the damaged machine, and Perry quickly moved towards it. The smoke was thicker closer to the contraption, and he waved one hand around in an attempt to clear it, trying to ignore the creeping, itching feeling along his body. Whatever Heinz had done this time, he hoped it wouldn’t be dangerous or require a school wide trip to the hospital.

Perry reached out for what he was pretty sure might be Heinz’s back, or maybe his chest. Instead, Perry’s fingers brushed over what felt like...feathers? Had they been experimenting with a bird?

The dark shape under Perry’s hand twitched and then suddenly shot up in a flurry of movement. Eerie purple light spilled from what looked like a giant wing, and Perry yelped, falling back away from whatever Heinz had accidentally created. Scrambling back on the heels of his hands, Perry stared as a pair of glowing eyes blinked open to look at him, nearly the same shade of purple as the wing.

Perry couldn’t seem to break eye contact, heart hammering in his chest and a shudder running through his body as he scrambled for something to defend himself with. Instead his hand came down on what he was pretty sure was a notebook, the sheer cover slipping over the tile floor. Perry slid with it, arm flying out from under him and his head knocking sharply against the corner of Heinz’s overturned desk. He had just enough time to briefly hope whatever the glowing thing was didn’t want to eat him before he fell unconscious.

* * *

Perry had been knocked out more than once in his life. Hell, he’d probably been knocked out more than a dozen times. He knew what to expect.

He did not, however, expect his body to feel so _weird_ as he slowly started to wake back up.

Hearing came first, rushing in like ocean waves of sound, disjointed and loud, like everyone was shouting.

“-think he knocked himself out?”

“Perrin- _oops_ , sorry-”

“-watch the tail!”

“Ohh, look, he’s got wings, too, Dad--ugh, get off, Johnny!”

“ _Per_ rin, wake up, come on now…”

“Should you really be talking, I mean what if you’re like me and--Johnny, I said _off_!”

Perry groaned, sensation rushing in next and not liking one bit of what he was feeling. He was pretty sure he’d either banged his head especially hard, or perhaps hurt his spine somehow, because everything about his body felt _wrong_. Even his teeth felt strange, sharp and pointed as he ran his tongue over them, trying to gather enough moisture in his mouth to swallow. He twitched a bit as he tensed his legs, which felt tangled in his pants, as though he was wearing a pair several sizes too small and too big at the same time.

“Look, he’s moving!”

“ _There_ we go, that’s it, come on, wake up.”

“You know he’s gonna be mad, right?”

“Oh, yeah, definitely.”

Perry let out a small growl of annoyance, wishing everyone would just stop _yelling_ for a minute. The sound came out deep and snarling, beast-like enough to startle even him, and blissful silence fell. He lifted one hand to rub it over his face, pausing when his fingertips brushed over his skin, tiny pinpricks of pain trailing after them.

“Ah, _care_ ful, Perrin, you’re _scratching_ yourself,” said a familiar voice, even more sing-songy than it usually was, a long-fingered hand wrapping around his wrist to pull his hand away from his face. Perry growled and the grip loosened for a moment before tightening again.

“Oh, wow, look at his _feet_!”

“Don’t touch him, you’ll get kicked.”

“Oh, _hi_ Peter! Wow, you look...oh. _Oh_.” Perry blinked his eyes open as Heinz’s voice took on a slightly hazy quality, his vision blurry and a little dark at first. He blinked some more and his eyes adjusted to the darkness of the classroom.

There was a crowd of people hovering around him, all of them looking….strange. Perry didn’t focus in on anyone too closely, eyes skating over them until he reached Heinz, who was kneeling to his left, one hand over his face, hiding his eyes, and the other still wrapped around Perry’s wrist. Perry squeezed his eyes shut and then opened them again, trying to figure out if he was imagining the broad pair of dark wings tucked behind Heinz’s back, or the faint glow from his hair and between the fingers over his face.

“Hey, Mr. Fletcher,” one of the students piped up, nearly unrecognizable under what appeared to be a layer of scales. “You okay?” Perry stared, eyes darting from one student to another. Almost all of them seemed to have become some sort of creature, sprouting wings or horns or tails. Some of them had turned transparent and were floating above the others, or were sitting half inside a desk.

Even Vanessa, standing a little to Perry’s left, had a pair of wings folded against her sides in place of her arms, tiny feathers dotting the skin of her face. Next to her was Peter, who looked relatively normal, though very pale. He met Perry’s eyes, looking concerned, and the bottom seemed to drop out of Perry’s stomach, a bit of a lurching feeling filling him, like when he’d had a really bad crush as a teenager. Confused that he was feeling that way while looking at _Peter_ , Perry stared at him, trying to make sense of the sudden and intense butterflies. Peter suddenly flushed and then looked away, the feeling vanishing and leaving Perry blinking rapidly as he tried to clear his head.

“Perrin?” Heinz squeezed his wrist and Perry looked back at him, trying to sit up. His back felt strange, his legs, too, and after a moment he looked down at himself.

His shirt was in tatters, like something had torn through the back and left the rest hanging in shreds around his upper body. His hands seemed slightly paw-like, with fingers tipped in claws and rough pads on the palms. Something twitched in the corner of his eye and he quickly turned to look at it, freezing as he realized there was a lion-like tail there, the tuft at the end the same color as his own hair.

“Heinz,” Perry rasped, barely audible, taking stock of his state as quickly as he could. Sharp teeth (fangs, really), claws, tail, and even his legs were different, a little longer, doubling back like a lion’s and apparently covered in a coat of dark teal fur going by the state of his toes. His pants had been unbuttoned and pulled down some, and Perry felt a faint flicker of embarrassment as he realized that most of Heinz’s students had probably seen the front of his green underpants.

Wondering why they’d felt the need to do that, he continued, “Did ye turn mae into a cat.” His voice was flat and rough, the words less a question than a statement, and a startled ripple of laughter moved through the room.

“ _Actu_ ally I think you’re some sort of _sphinx_ ,” Heinz said cheerily. “It’s the only thing from the index we inputted that’s both cat _and_ bird.” Frowning, Perry rolled his shoulders, trying to figure out why his back still felt so strange.

“Oi, watch it!” complained a student behind him. “You nearly smacked me in the face and Dr. D’s been doing enough of that for everyone.” Startled, Perry half turned around, pausing when an oddly colored wing came into view. It was holding very still, trembling just slightly, and when Perry reached out to touch it, he could _feel_ it. The wing was part of him, just like all the other odd changes Heinz’s explosion had caused.

Perry turned back and pulled his other hand sharply out of Heinz’s grip to sign, _what happened_.

“We were doing a genetics experiment,” Vanessa whispered, looking annoyed as Johnny swayed towards her, one of the few looking virtually unaffected by the explosion’s after-ripple.

“I...had a little _acci_ dent,” Heinz piped up from where he was crouched by Perry’s side, still hiding his face with one hand. His voice sounded the same as it always did, but Perry couldn’t help but think _music_ when he heard it. “The containment chamber _collapsed_ and then _exploded_. I’m not sure why. But, uh, I was demonstrating why mythological creatures didn’t _evolve_ scientifically and um. I _think_ I turned a bunch of us into monsters. Like we’re pretty sure you’re a sphinx. And I think Vanessa and I are some sort of _harpy_ or siren.”

 _Why are you covering your face?_ Perry demanded, glancing around at the other students, who all shuffled awkwardly.

“Well… he’s kinda _scary_ ,” one muttered, and Heinz twitched just slightly, wings drooping behind his back.

“He’s _not_ scary,” Vanessa snapped, and over half the room swayed as she lifted the edge of one wing to cover her mouth. “Dammit,” she muttered into her feathers, looking irritated.

“Well now we know who’s gay,” one student mumbled, eyeing the swaying girl next to her. Perry growled deep in his chest, the sound bubbling and guttural. Reaching over, Perry tugged Heinz’s hand down from his face to see that the man had tightly shut his eyes instead.

“Heinz, look at mae,” Perry murmured, patting the man’s cheek and trying not to scratch him. Heinz swallowed a bit, wings trembling.

“I don’t want you to be scared of me again,” Heinz whispered, looking a little ashamed. Perry frowned and scowled around at the group clustered around them.

 _I’m fine,_ he signed. _Go away_. Vanessa and Peter were the only ones to actually listen, shepherding the others away from where Perry and Heinz were sitting on the floor to start cleaning up the classroom.

“Johnny, go tell Principal Lang what’s happened,” Vanessa said, and the boy immediately scrambled to do as she said, nearly running down the hall in his haste.

Perry turned back to Heinz, trying to take advantage of what little privacy had been afforded to them.

Heinz had put his hand back over his eyes, head tilted down a bit. Perry gently pulled his hand away, knowing Heinz couldn’t see him signing with his eyes shut. So he just sighed heavily before leaning in and dropping a kiss on the man’s cheek.

That surprised him enough to make Heinz open his eyes, and Perry blinked against the bright purple glow coming from Heinz’s irises.

“You _kissed me_ ,” Heinz accused, his voice warbling a bit as he stared at Perry, a blush staining his pale cheeks. Perry shrugged, trying not to jump at the feeling of his new wings moving with the motion.

 _Needed you to look at me,_ Perry signed, grabbing Heinz’s chin to tilt his head from side to side, inspecting the man’s face. He looked almost the same, save for the faint glow in his eyes and in his hair.

“Nae scary,” Perry muttered, letting go of Heinz’s face, who was still blushing. _It was you I saw before I fell_. Perry pointed towards the DNA scrambler, which was little more than a smoking wreck. Heinz nodded, looking guilty.

“I didn’t mean to _scare_ you, but I was still kind of _groggy_ , and then you _touched_ me and I--sorry,” Heinz rambled, cutting himself off after a second, wings tensing and relaxing repeatedly behind his back. Perry shook his head and patted Heinz’s arm, looking down at himself and wondering how he was going to stand up with his legs all different. It shouldn’t be _that_ hard, right?

 _Why my pants?_ Perry asked, remembering that his slacks had been unbuttoned and pulled down. Heinz blushed even more deeply, glancing down at the soft bulge at the front of Perry’s underwear, visible in his open fly. The purple glow in his eyes flared for a second as he looked back up, swallowing hard.

“Your tail,” Heinz said simply. Perry reached behind himself to touch at his lower back, feeling his spine elongate out into the tail right above where the crack of his ass started. It would indeed have been uncomfortable to have that trapped in his underwear.

 _Not a student, right?_ Perry asked, frowning.

“Oh, no, _no_ , I-- _I_ was the one to-- I did the--” Heinz stammered for a second, blushing as his wings dropped down and forward to sort of wrap around his body as he blurted, “I pulled your pants down, Perrin, I’m _sorry_.” Perry fought back the urge to laugh at Heinz’s obvious embarrassment, giving the man a thumbs up. Out of everyone that had been around, Heinz was the only person Perry was even vaguely okay with taking articles of his clothing off. Not that it had the same context that Perry was usually thinking of, but in general the rule still applied.

Heinz gave him a tiny, shy smile before climbing to his feet, wings flaring out for balance. Perry stared a bit as the feathers spread out, a bright lilac glow coming from the inner sides. Despite the strangeness of the entire situation, he could appreciate that Heinz was...sort of beautiful, like that. Glowing and almost angelic with his large wings and suddenly musical voice.

“Do you want to try _stand_ ing? I know _Karen_ fell when she first tried, but you’ve gotta get up _some_ time,” Heinz gave a nervous laugh, holding out a hand that Perry took after a second. He tried not to prick Heinz with any of his claws as he tightened his grip, bracing his other hand on the desk he’d fallen into and pushing himself to his feet.

He fell almost immediately.

Heinz lurched forward and caught him, wings spread out almost to their full length as he wrapped his arms around Perry’s torso.

“ _Care_ ful!” Heinz gasped, fingers digging into the line of fur-like feathers that ran down Perry’s spine between his own, much smaller, pair of wings. Perry nodded frantically, heart pounding as he resisted the sudden urge to rub his face all over Heinz’s chest, which was covered only by a few scraps of his own shirt. Perry supposed it’d been destroyed when he’d sprouted wings, just like Perry’s.

Trying to support his own weight again, Perry swayed and clutched at Heinz’s arms, wincing when the man hissed, Perry’s claws scratching at the artificial skin.

 _Sorry,_ Perry signed one-handed as he tried to figure out how feline hind legs worked.

“Try-try balancing on your _toes_ ,” Heinz pointed out. “Cat feet are different than human feet. Lean _for_ ward a bit. Sp-spread your legs some.” Heinz blushed furiously at the last sentence and so did Perry, even as he did as Heinz instructed. He also tried shifting the way he held his hips, and after a second, settled into a stance that felt far more stable. Letting go of Heinz’s arm, Perry stood on his own, taking total stock of his new form.

It was not a form he was very happy about having, but Heinz had done worse to him before with the de-evolution-inator, and was sure he’d be able to fix this, given enough time.

Nodding, Perry gave Heinz a thumbs up, grinning a bit. The grin vanished when Heinz had to duck away to avoid getting smacked with one of Perry’s wings that had jerked up with his excitement at being able to stand.

 _Sorry, sorry!_ Perry quickly signed, trying to work out which muscles in his back controlled the wings. After a minute he managed to figure out how to tuck them against his spine, holding them there tightly as Heinz grinned at him.

“Okay, well, I guess I better get on how to change us _back_ , right?” Heinz asked, jerking a thumb over his shoulder at where Peter was picking through the wreckage of the machine, frowning a bit with Ortega crouched next to him, looking like an excited cat, a long tail swaying back and forth from under his jacket.

Perry forgot about Ortega and his tail as he looked back at Heinz, who was still smiling at him. Perry gave him another thumbs up, before looking back down at himself and wondering what he was going to wear when he had wings and a tail. He couldn’t quite wear pants, unless he wanted to cut holes in all his jeans, or wear them riding indecently low. A skirt would probably take care of that, but he wasn’t so sure about a shirt. Maybe if he cut holes in the back? He had a couple old tees that could take it.

“ _PERRY_!” a familiar voice shrieked from outside the classroom, and he immediately jerked into motion at the sound of Candace so distressed. Heinz yelped as Perry shoved past him, paternal instinct taking over as he scrambled for the hall. He adjusted to his new lower half as quickly as he could, tail whipping out and wings extending for balance as he scratched up the floor with his hind claws, hands flying out to grab at the wall and doorframe so he wouldn’t fall on his face.

Candace was standing outside of Perry’s classroom, hands clamped tightly to the top of her head, fingers fisted in her hair. She turned at the sound of him half-skidding into the hall, mouth falling open a bit at his appearance.

“What are _you_ supposed to be?” she demanded, eyes wide. She looked like she’d been crying, cheeks streaked with tears and a little bit of smudged make-up.

 _S-P-H-I-N-X, we think,_ Perry signed quickly, tail lashing and wings flared up high behind his shoulders. _What’s wrong?_

“M-my head,” she stammered, staring up at him. He looked her over, trying to see if she’d been affected by Heinz’s accident. She looked mostly normal, save for her state of panic.

 _Hurts?_ Perry demanded, wondering if Heinz’s machine could have caused some sort of internal damage to Candace instead of just turning her into a creature.

“N- _nooo_ ,” she cried, still holding onto her hair like her head was about to fall off.

 _What?_ Perry asked, at a loss. She bit her lip and looked down.

“It’s...freaky,” she muttered, and Perry frowned at her.

 _Show me,_ he demanded, wondering if she was hiding horns under her hands or something. Seriously, with the way _he_ looked, he didn’t understand why she was so upset.

“My….my head comes _off_!” Candace cried, raising her arms and lifting her head clean off her neck, as though she’d been beheaded.

Perry stared for a moment, unable to believe his eyes as Candace held her head in her hands in front of her chest like a bizarre basketball, her face distraught.

“ _Candace_ ,” Perry wheezed, feeling suddenly very dizzy and reaching out to touch her.

* * *

 

The next thing Perry knew, he was laying on the floor in the hall, a group of people clustered around him again. This was becoming an annoying habit.

Heinz was closest, wings spread out and up to force most of the others back.

“Okay, _okay_ , give him some _space_ , Jesus, the guy _fainted_ alright, what do you _expect_ ,” Heinz snapped, glaring at anyone who tried to edge in closer, batting at them with one wing. Candace and Vanessa were huddled under the other, Vanessa’s own wings wrapped around Candace’s body as she held her head on top of her neck and cried into her shoulder.

Perry groaned, wondering how he’d managed to end up unconscious twice in an hour. That had to be some sort of record, if only a personal one.

“ _Per_ rin?” Heinz jerked his head around to stare down at Perry, face worried. “You _okay_? Vanessa explained that Miss Flynn is _family_ of yours--” Perry groaned again.

“I d-didn’t _mean_ to!” Candace sobbed, not looking up from where she was buried in Vanessa’s feathers. “I’m s- _sorry_ , P-Perry!” Perry put both hands over his face and prayed for the strength to navigate the very dangerous waters he was fording between his two _very_ complicated lives. When he was sure he could sit up without vomiting, Perry pushed himself up into a sitting position and waved at Vanessa until she looked at him.

 _Give her to me_ , Perry signed, gesturing at Candace. Vanessa gently pushed the redheaded teen away and towards Perry, and Candace blinked open red-rimmed eyes to stare at him, looking guilty and horrified with herself. Perry reached out and pulled her down against his chest, petting her hair and shoulders and back.

“I’m s-sorry,” she said again, and Perry felt guilty for upsetting her so much.

 _No, my fault. Just scared me. Bad,_ Perry signed, pushing her away so she could see. She chewed her lip, still holding her head on her neck.

“What happened? Why-why am I--and you, and everyone else?” she asked, glancing around. “Phineas and Ferb…?”

“Nope, that’d be _my_ fault!” Heinz said cheerily, waving one hand, the wing behind him mirroring the movement. “Like with the _gel_ atin a few weeks ago.

“I think you’re a _Dullahan_ ,” Heinz added, leaning down to inspect Candace’s neck, his slightly luminescent hair brushing against Perry’s face. “You _know_ , like the Headless _Horse_ man. They’re some sort of _ghost_.” Perry blinked, then reached up to cover Candace’s eyes.

“Hey!” she protested, trying to lean back but unable to dislodge him, too busy holding her head on.

Perry snapped his fingers frantically to get Heinz’s attention before pointing to Candace and spelling out, _D-E-A-D?_ Heinz blinked at him, and then considered Candace again, pursing his lips a bit, glancing over to take in Perry’s distraught expression.

Perry didn’t know what he’d do if Candace _died_ because of one of Heinz’s experiments gone wrong.

After a moment of hard thought, Heinz finally said, "Don't _wo_ rry, Perrin! She’s not _act_ ually dead. ...Okay maybe a little bit. Like, 75%, tops. Should change right back to normal human being when I fix the scrambler. I think."

“Wait, _dead_?” Candace demanded, finally giving up and lifting her head off her neck again so she could get away from Perry’s hand and see. She glared at Perry, head in her own lap as he tried not to feel queasy again just looking at her. That would take some getting used to.

“Are you talking about me?” she asked, eyes narrowed in suspicion. Perry shook his head and she glowered at him. “You’re a terrible liar!” she snapped, jumping to her feet and striding away, placing her head back on her shoulders as she went. Perry stared after her, feeling a bit at a loss.

“Let her blow off some _steam_ ,” Heinz said, waving a hand. “You okay? You looked pretty, uh, freaked out to see her head come _off_ like that.”

 _She’s like my daughter,_ Perry signed sharply. _Of course I reacted badly_. Heinz shuffled a bit, nodding and holding out a hand to help Perry up. Perry nearly tripped again, stumbling to get his feet under him.

“I-I think it’s because your-- _um_.” Heinz gestured awkwardly at Perry’s pants, which were slipping further down his thighs than what was even close to decent. Perry blushed, catching Heinz eyeing his crotch again. A low, rumbling sort of noise sounded from deep in Perry’s chest, and they both startled at it. Yanking his pants up as high as he could get them, Perry blushed more deeply as Heinz eyed him uncertainly.

“Did...was that a...  _growl_? It kinda _sound_ ed like a growl, but at the same time... _not_ ,” Heinz peered at Perry, who waved him off and pointed back at the classroom. “Oh, yeah, Peter and his friend, the...you know, I can’t remember what he _looks_ like?” Heinz laughed before continuing, “But they’re working on the machine. Trying to figure out what went wrong.” Perry nodded, trying to recall what Peter’s coworker looked like himself, and finding that he couldn’t. Odd, he was usually better with faces than that. Though he _had_ only met the man moments before the explosion and consequential head-meeting-desk scenario. That was probably why.

 _How far out?_ Perry asked after a moment, realizing that Candace’s class, which was nearly on the other side of the school, had been affected. How far had the ripple spread? Just the high school? The elementary school across the street? All of Danville? Heinz shrugged, pulling his wings back against his spine.

Frowning, Perry walked a little ways away from Heinz, who was quickly distracted by Vanessa, tapping at his watch until it lit up. Checking news feeds and a few other websites, Perry learned that the ripple had only affected people in maybe a two mile radius from Heinz’s classroom, including the elementary school. So with Perry’s luck, all of his kids had been affected by the machine. He just had to hope that none of the others had been turned into undead creatures. He had enough on his plate as it was.

It was a foolish hope.


	2. Chapter 2

Since much of the Danville area was thrown into chaos after Heinz’s accident, school let out early, a half-strangled announcement from Lang sending throngs of students spilling outside, most of them taking on some form of creature from the index Heinz had punched into the machine before it had blown up. Luckily Heinz had a paper version as well, and was flipping through it absently while Perry followed him outside, looking around to see who all had been changed. 

Perry spotted Pinky trying to calm an irate Isabella, who’d apparently run over from the elementary school next door. Perry stared in mild alarm at the fact that both of them appeared to be little more than skeletons, clothes sagging over bony appendages, yellow lights glowing in their dark eye sockets.. Blinking, Perry craned his neck to see past Heinz, noticing that most of the elementary students had made their way over to the high school, looking for older siblings or parents who’d been called after the explosion. 

He didn’t seen Phineas anywhere yet, but something small, green, and silent came barreling up to him, and Perry quickly crouched as the speeding projectile nearly bowled over Heinz to get to him. 

Ferb had grown wings as well, though his were like a bat’s rather than a bird’s, thin and delicate behind his back. His skin had taken on a distinctly grey-ish green tone, hair darkening to a shade so dark green it was almost black. 

“Per!” Ferb gasped, clawed fingers digging into Perry’s neck as he hoisted the boy up into his arms. Heinz eyed him curiously, feathers twitching a bit behind him. 

“How many kids do you  _ have _ ?” Heinz asked after a minute. Perry just shrugged, wings drooping forward and around to wrap Ferb in a feathery cocoon. 

Ferb usually took the odd things in his life in stride, so Perry was a little concerned to see him so upset. Rubbing his cheek against the top of the boy’s head, Perry hugged him tighter, stepping off the front steps of the school and into the grass of the front lawn. Heinz peeked at Ferb from over Perry’s feathers and arms, frowning a bit and flipping through his index. 

“It’s going to take a  _ while  _ to figure out what everyone even  _ is _ ,” he muttered, mostly to himself. Perry just continued to indulge in rubbing his cheek against Ferb’s hair, a content feeling stirring in his chest. Heinz glanced up as he pursed his lips, apparently trying not to laugh. 

“You are scenting the  _ heck  _ out of him, I can smell it from here,” Heinz commented, one hand coming up to cover his mouth when Perry stilled. 

Frowning, Perry paused before sticking one hand out of the shelter of his wings to spell  _ B-A-D? _

“Oh, no,  _ no  _ it’s--it’s like  _ bond _ ing, you know, when cats rub their face against stuff? It’s like stamping a big fat  _ ‘mine’  _ on it,” Heinz explained, fumbling with the index a bit. “And it doesn’t smell  _ bad  _ at least, not to  _ me _ . I mean that’s a little  _ odd _ , usually separate families don’t  _ like  _ the smell of each other.” Heinz gave a nervous laugh, and Perry made that not-quite-a-growl noise, startling Ferb a bit where he was curled against his chest. Heinz started a little too at the sound, a faint flush appearing on his cheeks as he cleared his throat and started flipping through the index again, not even pretending to read it. 

Perry tried not to blush as well, lifting his wings a bit so he could see Ferb’s face. He looked upset, features scrunched as he buried his nose in Perry’s chest, eyes screwed shut and new claws scratching at Perry’s skin. Perry bounced him a bit, trying to get him to look at him. Ferb just shook his head frantically, and Perry blew out a breath. Bouncing him again, more firmly, Perry got him to open his eyes, which were large and wet and still their familiar brown color. 

“Ph-Phineas,” Ferb stammered, and then buried himself back in Perry’s arms again, refusing to say another word. Worry trickled down Perry’s spine and he wrapped his wings tight around his body, shielding Ferb as he looked around for the last of his kids. There was no sign of him, and Perry let out a frustrated growl. He started looking for Candace instead, who was as reliable of a Phineas-detector as there was. 

She was a few dozen yards away, standing with Stacy and Vanessa, Pinky joining them after a moment with Isabella clinging to his fingers. Candace had apparently given up trying to hold her head on, and had instead wrapped a scarf around her neck and was holding her head in front of her chest again. Stacy looked unaffected, both by the state of her best friend and by the machine, chatting excitedly with her and admiring Vanessa’s feathers. 

No help there, Perry thought, sighing. 

“Perry! Wow, look at you! Have you seen Ferb?” a disembodied voice piped up right next to his head, and Perry jumped what felt like half a mile, propelling himself into Heinz on accident. They went down in a mess of limbs and feathers and colorful German, ending up tangled on the lawn with Ferb trapped between them. 

“Sorry! Jeez, I’m surprising everyone today!” the voice said again, and Perry felt his stomach drop as he recognized it. Lifting his head to glare down at Heinz, Perry tried disentangling himself from the man but just ended up knocking him in the head with one of his wings. 

“ _ Ow _ ,” Heinz complained, ceasing his own struggles and just laying on his back while Perry tried to free himself. One of Heinz’s hands came up to cup around Ferb’s stomach where the boy was laying on him, looking startled by the sudden fall. Ferb’s nostrils flared when Heinz’s hand came to rest on him, relaxing after a moment and grabbing onto Heinz’s fingers. Perry managed to sit up, trying not to kneel on Heinz’s wings or scratch him at all. 

_ Phineas? _ Perry signed, looking around, but only seeing a few clusters of students eying them and laughing a bit. Perry scowled, tail jerking free from under Heinz to lash back and forth in irritation. 

“Yeah, I’m right here!” Perry peered in the direction of Phineas’s voice, and was only able to make out a very faint blue glow, that was possibly in the shape of his youngest cousin. “I’m barely visible in daylight apparently, but you should see me in the dark! We were watching a movie in Social Studies and then BAM! I’m glowing like a night light! And then I fell through my  _ chair _ ! Do you know what happened? Ferb turned  _ green!  _ And you’ve got wings! That’s so cool! And a tail, too! Have you seen Candace? Her  _ head  _ comes off now!” Perry let Phineas ramble, hesitantly reaching out to try and touch him. HIs fingers passed right through what he was reasonably sure was Phineas’s stomach, startling a giggle out of him. “That feels weird!” 

Perry groaned and leaned down to press his forehead against one of Heinz’s thighs. Heinz twitched in surprise but otherwise didn’t move as Perry grumbled wordlessly into his leg. 

It looked as though the monster traits were running in families, what with him and Ferb being winged beasts, the Garcia-Shapiros becoming skeletons, Heinz and Vanessa being siren or harpy-like, and now both Flynn children being some sort of ghost. 

“Perrin?” Heinz piped after a second, voice warbling uncertainly. Perry held up a hand, not bothering to sign anything but inviting the man to speak. “If-if you’ll just let me check my  _ index _ , I’m pretty sure of what he is, I mean-” Sighing, Perry sat up and reached out to pluck Ferb off where he was lying on Heinz’s chest and set him back on his feet. Ferb shuffled and glanced over at the general direction of Phineas, wings trembling behind his back. Perry didn’t even bother resisting the urge to lean down and rub his cheek against Ferb’s as Heinz sat up to grab his book from where it’d fallen. Ferb let out a small growling noise and pushed at Perry until he stopped, but the scenting was enough to ease a bit of Perry’s ire. 

“Ah, _here_ we go!” Heinz said triumphantly, pointing at a page in his book. “‘A _will-o'_ -the-wisp, or _ignis fatuus_ , is an atmospheric _ghost_ light seen by travelers at night, especially over bogs, swamps or _marsh_ es. It resembles a flickering lamp and is said to recede if _approach_ ed, drawing travelers from the safe paths.’ See? He’s only visible at _night_. Or-or, in the _dark_ I guess.” Perry just grumbled again, holding up two fingers. Heinz blinked at him, not understanding. 

_ Two of mine _ , Perry elaborated.  _ Seventy five percent?  _ Heinz’s eyes widened and then gave a little nervous laugh. 

“O _ oh _ , yeah, I guess. Well, I told you, I’m  _ sure  _ they’ll change right back once we get the scrambler fixed. Though I suppose this isn’t  _ really  _ a DNA problem, it’s not like we  _ mixed  _ ourselves with anything, just changed  _ form… _ ” Heinz frowned thoughtfully, flipping through his index some more. “I may need to make a whole new  _ inator _ .” Perry rubbed at his forehead, a throbbing headache taking root under the goose egg he had from hitting his head earlier. While Heinz could  _ build  _ an inator in a day, it usually took him  _ weeks  _ to plan it out and go through a few prototypes. They could all be stuck like this for a while. 

_ Great,  _ Perry signed, glancing between Ferb, who was looking nervously at Phineas every few minutes, and Heinz, who was still looking in his index, rubbing at his chin. 

Just great. 

**Notes for the Chapter:**

> I'm not sure when/if I'll be writing a third chapter for MM, but I've had a couple of people ask for a second part, and this has been sitting unfinished in my drafts for long enough. Sorry for the wait. <3


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